I think you have two problems. Your alternator is not currently charging as it should, but I doubt that it has anything to with the drain. To ensure that this is the case, disconnect the plug at the alternator, then put an ammeter in series with a battery cable. You should get very little, if any, current draw. Certainly no more than 100 milliAmps. If you get no current draw, plug in the alternator connector and see if it increases, if it does, then the alternator is indeed the source of the draw.
I expect the current draw is somewhere else. With your ammeter in place, begin removing fuses and disconnecting things until it goes away. Whatever you disconnect that makes the current draw significantly decrease, is the circuit with the problem.